Pyrotechnic safety device and method of use

ABSTRACT

A pyrotechnic safety device having a heat and flame resistant conduit coupled with a pyrotechnic device is provided. The conduit remains coupled to the pyrotechnic device during autoignition of the pyrotechnic device and dissipates the energy of a gas discharged by the pyrotechnic device as a consequence of the autoignition. Also disclosed is a method of preventing projectile movement of a pyrotechnic device comprising the steps of coupling together a pyrotechnic device and a heat and flame resistant conduit and allowing the conduit to dissipate the energy produced by a gas generated by the pyrotechnic device as a consequence of autoignition.

FIELD OF THE INVENTION

The present invention relates generally to an apparatus for use with the transport of a pyrotechnic device, and more specifically to an apparatus and method for safely transporting an air bag inflator used in vehicle air bag safety systems.

BACKGROUND AND SUMMARY

This invention generally relates to the field of transportation of pyrotechnic systems such as for example and without limitation a vehicle airbag system having a pyrotechnic device such as an initiator in combination with an inflator. Several references disclose the operation of conventional airbag systems, including, for example, U.S. Pat. Nos. 5,454,593; 5,683,102; and 6,669,226, the disclosures of which are incorporated herein by reference. One or more conventions, rules, guidelines or regulations, including without limitation regulations of the United States Department of Transportation and a United Nations document entitled “The Recommendations on the Transport of Dangerous Goods Manual of Tests and Criteria,” which is incorporated herein by reference, require that pyrotechnic devices be somewhat heat and flame resistant during transport or travel. For example and without limitation test 6 a of The Recommendations on the “Transport of Dangerous Goods Manual of Tests and Criteria” describes a bonfire test that such a pyrotechnic system or device must undergo and pass.

An illustrative inflator may contain pressurized gas, which is released or discharged into the airbag when the igniter ruptures the inflator under normal conditions. The igniter may also rupture the inflator causing discharge of the pressurized gas under abnormal conditions such as caused by a fire, flame, or excessive heat as described in the bonfire test of test 6 a noted above. An abnormal condition may also melt the passageway by which the discharging gas normally is vented into the airbag. If such an abnormal or high heat condition occurs during transport of the pyrotechnic system or the pyrotechnic device, then the energy or force of the discharging gas may cause the pyrotechnic device to shoot off like a missile or other projectile. What is needed is a pyrotechnic safety device that dissipates the energy of the discharging gas.

The pyrotechnic safety device disclosed herein comprises one or more of the features identified in the various claims appended to this application and combinations of such features as well as one or more of the following features or combinations thereof. A pyrotechnic safety device generally comprises a pyrotechnic device, a conduit or hose, and airbag, and an airbag input channel. The pyrotechnic device is equipped coupled to the conduit or hose. The hose is generally flexible and heat and fire resistant. The hose illustratively may have a rubber or silicon rubber outer layer surface and a fiberglass inner layer or surface. The hose remains coupled to the pyrotechnic device during an abnormal event such as fire or high heat. If the abnormal event causes autoignition of the pyrotechnic device and a resultant discharge or release of pressurized gas, then the hose will dissipate the energy of the discharged gas. The hose may receive therein an input passageway having one end in fluid communication with the pyrotechnic device and another end in fluid communication with an airbag. A method of preventing projectile movement of a pyrotechnic device comprising the steps of coupling together the pyrotechnic device and a heat and flame resistant conduit, configuring the conduit to remain coupled with the pyrotechnic device when the pyrotechnic device is subjected to a heat source sufficient to cause autoignition of the pyrotechnic device, and allowing the conduit to dissipate the energy produced by a gas generated by the pyrotechnic device as a consequence of autoignition is also disclosed.

These and other features of the present invention will become more apparent from the following description of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagramatic view of an illustrative pyrotechnic safety device.

FIG. 2 is a sectional view through an illustrative conduit depicted in FIG. 1 taken generally along the line 2-2.

FIG. 3 is a sectional view through an illustrative conduit and input passage way depicted in FIG. 1 taken generally along the line 3-3.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to an illustrative embodiment depicted in the drawings. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.

Referring now to FIG. 1, there is shown an illustrative pyrotechnic safety device or system 20 comprising generally a pyrotechnic safety device or conduit 10, a pyrotechnic device 22, an airbag 18, and an airbag input passageway 16.

The pyrotechnic device 22 generally includes in combination an igniter or initiator and an airbag inflator. The pyrotechnic device 22 generally is in fluid communication with the air bag 18. For example, the airbag input passageway 16 is coupled to the output of the inflator of the pyrotechnic device 22. The passageway 16 illustratively may comprise a tube and/or a tube within a sleeve, which, like the airbag 18 may be fashioned out of any material suitable for containing hot expanding gases such as for example and without limitation nylon 12, nylon 6,6 or polyester fiber.

As best seen in FIG. 2, the pyrotechnic safety device or conduit 10 generally comprises a heat and flame resistant outer surface or layer 12. For example and without limitation, the outer layer may be fashioned out of a rubber material, such as for example and without limitation a silicon rubber, or of a ceramic or composite material that is heat and flame resistant. It will be appreciated however that any heat and flame resistant material capable of passing the bonfire test may be used. Illustratively, the conduit 10 has an elongated cylindrical cross section, although conduits with other cross sections fall within the scope of the invention. For example and without limitation, the conduit 10 may be an elongated tube or a hose 10. Illustratively, the conduit or hose 10 is flexible or semi-flexible and may comprise an inner layer 14. The inner layer 14 may be for example and without limitation fiberglass or other suitable material. The inner layer may, for example and without limitation, be homogeneous, or may instead be braided, interwoven, or the like. In addition to providing some structure to the conduit 10, it may also provide further heat and flame resistance. The outer layer 12 may or may not be bonded to the inner layer 14.

Referring to FIG. 3, it can be seen that the hose or conduit 10 is sized to receive therein the airbag passageway 16, which is in fluid communication with the airbag 18 and the inflator or pyrotechnic device 22. Illustratively, hose clamp 15 is fitted around the conduit or hose 10 and the passageway 16 received within the hose 10 in order to couple together the hose 10, the passageway 16 and the pyrotechnic device 22. It will be appreciated that the passageway 16 need not extend all the way through the hose 10, but instead could be coupled to the hose separate and apart from the pyrotechnic device 22, such that one end of the hose 10 is in fluid communication with the pyrotechnic device 22 and the other end of the hose is in fluid communication with the passageway 16.

The assembled pyrotechnic safety system 20 has the airbag input passageway or tube 16 received within the conduit or hose 10, which hose 10 is coupled with the pyrotechnic device 22, and the airbag input passageway is coupled in fluid communication at one end with the pyrotechnic device 22 and in fluid communication at the other end with the airbag 18. When the pyrotechnic safety device or system 20 is subjected to abnormal heat or flame such that autoignition of the pyrotechnic device 22 causing the discharge of pressurized gas from the inflator, then all or a portion of the input passageway may melt or disintegrate. So too, portions of the conduit or hose 10 may melt; however, the structural integrity of the hose 10 will substantially be retained and the hose 10 will remain coupled to the pyrotechnic device 22. For example the outer layer 12 and/or the inner layer 14 may retain its structural integrity. The retention of this structural integrity will allow the discharged gas to be received within the hose 10 and/or within the portions of the input channel received within the hose or conduit 10. The hose 10 and/or the portions of the input channel received within the hose or conduit 10 will illustratively flap about as the discharged gas is received therein and exhausted at the end that is no longer connected to the airbag 18. Because the hose flaps about, there is insufficient directed thrust to cause the pyrotechnic device to become a projectile or to fly off in a projectile motion. Of course, if the abnormal event is sufficient to causes autoignition but insufficient to melt the input passageway 16 such that the airbag 18 is still in fluid communication with through the passageway 16 with the pyrotechnic device 22, then the discharged gas will inflate the airbag 18 and the pyrotechnic device 22 will not become a projectile.

Illustratively, the hose or conduit 10 may be any suitable length. Tests have proven that a hose or conduit 10 about 12 inches in length are suitable to dissipate the energy of the gas discharged due to an abnormal autoignition event. Conduits or hoses in excess of 12 inches are also suitable to dissipate the energy generated by autoignition. In addition, conduits or hoses of less than 12 inches in length, for example and without limitation, hoses about four inches in length or greater fall within the scope of the invention.

A method of preventing projectile movement of a pyrotechnic device comprises the steps of coupling together a pyrotechnic device 22 and a heat and flame resistant conduit 10. The conduit is configured 10 to remain coupled with the pyrotechnic device 22 when the pyrotechnic device is subjected to a heat source sufficient to cause autoignition of the pyrotechnic device 22, and the conduit is allowed to dissipate the energy produced by a gas generated by the pyrotechnic device as a consequence of autoignition.

While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 

1. A pyrotechnic safety device comprising: a heat and flame resistant conduit, the conduit being coupled with a pyrotechnic device.
 2. The pyrotechnic safety device of claim 1 wherein the conduit comprises a tube.
 3. The pyrotechnic safety device of claim 2 wherein the tube comprises hose.
 4. The pyrotechnic safety device of claim 3 wherein the hose has a generally cylindrical cross section.
 5. The pyrotechnic safety device of claim 1 wherein the conduit has a length of about four inches.
 6. The pyrotechnic safety device of claim 1 wherein the conduit has a length greater than or equal to about four inches.
 7. The pyrotechnic safety device of claim 1 wherein the conduit has a length greater than or equal to about twelve inches.
 8. The pyrotechnic safety device of claim 1 wherein the conduit substantially retains its structural integrity when subjected to temperatures sufficient to cause an autoignition of the pyrotechnic device.
 9. The pyrotechnic safety device of claim 8 wherein the autoignition causes the pyrotechnic device to discharge a gas and wherein the conduit remains coupled with the pyrotechnic device and dissipates a force produced by the discharging gas.
 10. The pyrotechnic safety device of claim 9 wherein the conduit inhibits projectile movement of the pyrotechnic device caused by the discharging gas.
 11. The pyrotechnic safety device of claim 1 wherein the conduit inhibits projectile movement of the pyrotechnic device when the pyrotechnic device is subjected to a bonfire test prescribed by regulation or convention.
 12. The pyrotechnic safety device of claim 11 wherein the bonfire test is substantially as described in a document entitled The Recommendations on the Transport of Dangerous Goods Manual of Tests and Criteria extant in June
 2004. 13. The pyrotechnic safety device of claim 12 wherein the conduit has a length greater than or equal to about four inches.
 14. The pyrotechnic safety device of claim 12 wherein the conduit has a length greater than about eleven inches.
 15. The pyrotechnic safety device of claim 9 wherein the conduit is fashioned out of rubber.
 16. The pyrotechnic safety device of claim 9 wherein the conduit is fashioned out of silicon rubber.
 17. The pyrotechnic safety device of claim 9 wherein the pyrotechnic device comprises an airbag inflator.
 18. The pyrotechnic safety device of claim 17 wherein the conduit comprises an outer layer fashioned out of rubber and an inner layer fashioned out of fiberglass.
 19. The pyrotechnic safety device of claim 18 further comprising a clamp that fits over the conduit and the output end of the airbag inflator, the clamp being adjustable to couple together the conduit and the airbag inflator.
 20. The pyrotechnic safety device of claim 19 further comprising an airbag, the airbag having an input passageway in fluid communication with the airbag, the conduit configured to receive therein the input passageway of the airbag such that the inflator and the input passageway of the airbag are in fluid communication.
 21. The pyrotechnic safety device of claim 20 wherein clamp couples together in fluid communication the inflator and the input passageway of the airbag.
 22. An pyrotechnic safety device comprising: an airbag inflator, a hose coupled with the airbag inflator, the hose being heat and flame resistant such that the hose substantially retains its structural integrity and remains in coupled with the airbag inflator in order to dissipate a force of a gas discharged by the airbag inflator when the pyrotechnic device is subjected to temperatures sufficient to cause an autoignition of the airbag inflator in order to inhibit projectile movement of the airbag inflator.
 23. The pyrotechnic safety device of claim 22 wherein the hose has a length of greater than about eleven inches.
 24. The pyrotechnic safety device of claim 22 further comprising an airbag having an input passageway in fluid communication with the airbag, the input passageway being in fluid communication with the airbag inflator when the input passageway is received within the hose.
 25. A method of preventing projectile movement of a pyrotechnic device comprising the steps of: coupling together a pyrotechnic device and a heat and flame resistant conduit, configuring the conduit to remain coupled with the pyrotechnic device when the pyrotechnic device is subjected to a heat source sufficient to cause autoignition of the pyrotechnic device, allowing the conduit to dissipate the energy produced by a gas generated by the pyrotechnic device as a consequence of autoignition. 